extended-tracker

extended-tracker (temporary name) is a declarative language and a suite of tools for interactive music and live coding.

Drawing its inspiration from music trackers, it allows describing MIDI note sequences in a human-readable syntax.

Root = [
    # start

    $ player speed: 100 / 60
    $ head stepDuration: 1/2
    
    p: 69, v: 80
    p: 64, v: 60
    p: 76, v: 60
    ,
    ,
    -

    @ start
]

An overview of the language can be found here.

Install

With NodeJS installed, follow these steps:

git clone https://github.com/pckerneis/extended-tracker
cd extended-tracker
npm install

Run in a terminal

You can start a player in the terminal with:

npm run start

You'll have to specify a program file to read from, the program's entry point (the name of the declaration that should be read first) and a MIDI ouput.

There are a few command-line options in order skip the prompts:

npm run start -f programs/lullaby.txt -e Root -o 0

Run in a browser

In order to generate a JavaScript bundle, run the command:

npm run build-web

The bundle is located in dist/web/bundle.js.

There a demo page located in static/web-demo.html. Note that Firefox does not support WebMidi.

Repository content

• src/common/ Platform-agnostic code for most of the utility classes (scanner, parser, player...)
• src/node/ NodeJS-specific code
• src/web/ Browser-specific code
• static/ A web demo showcasing usage in a browser
• programs/ A bunch of test programs used for debugging

Project architecture overview

• The Scanner and the Parser are responsible for building an AST representation of a program.
• The Player is a time keeper and a scheduler. It is responsible for creating the main reader Head.
• A reader Head moves from a sequence step to another, evaluating AST portions on the fly and spawning child heads.
• Platform-specific MidiOutput objects are responsible for sending the MIDI messages.

Getting involved

I'd greatly appreciate feedback and help.

Pulls requests are welcome!